In recent years, fuel cells that generate electricity by means of an electrochemical reaction of hydrogen and air have attracted attention as a source of energy. A fuel cell produces electromotive force by means of an electrochemical reaction of hydrogen and air. Hydrogen to be supplied to a fuel cell is obtained, for example, by using a hydrogen separation unit to separate hydrogen from reformed gases derived by reforming a hydrocarbon feedstock.
Known hydrogen separation units include, for example, devices that utilize hydrogen permeable metal having the quality of selectively passing hydrogen, such as palladium or palladium alloy. With such a device, when reformed gases are supplied to a first side of the hydrogen-separating metal, hydrogen is extracted at the other side. Conventional hydrogen separation units are fabricated, for example, by initially fabricating a hydrogen permeable substrate that formed palladium coating on vanadium (which is also a hydrogen-separating metal), then stacking various parts such as flow channel plates and a top panel on the hydrogen permeable substrate and joining them by means of diffusion bonding, laser bonding, or other joining process.